Propolis is biologically a mixture of sap with secretions from the bee's salivary glands, which is used to seal the hive, help preserve honey, protect the development of larvae, eggs and itself from the attack of pathogens.
Among bees, Italian bees (Apis melifera, Apini tones) and Du wasps (also known as stingless bees) (Meliponini tones) give much propolis and have drawn interest from researchers. Unlike Italian bee Apis melifera, the Du is rich in number of species, with more than 500 species in the world, distributed in many different geographical areas. In Vietnam, according to previous studies, there are more than 10 different species of the Du.
Propolis has long been used in the treatment of colds, rheumatism, diabetes, stomach pain, and has many biological activities that have been discovered such as antibacterial, antioxidant, anti-cancer and anti-HIV. Due to many practical applications such as medicine products and functional foods, propolis has attracted a lot of research on chemical composition and biological activity.
Currently, scientists have isolated more than 500 compounds in honey propolis as well as Du propolis in the world. The chemical composition of propolis includes phenolic acid compounds, phenolic esters, flavonoids, triterpenes, stilbenes and prenyl flavanoids. However, there has not been much research on the chemical and biological activity of propolis in Vietnam.
In the framework of international cooperation, scientists from the Institute of Marine Biochemistry and the Institute of Ecology and Biological Resources, VAST, coordinated with Bulgarian scientists from the Institute of Organic Chemistry with the Center of Plant Chemistry to carry out a project "Searching for bioactive compounds from Vietnamese propolis" - code: VAST.HTQT.BULGARIA.02/17-18, from 2017 to 2018, by Dr. Le Nguyen Thanh, Vietnamese, and Prof. Dr. Vassya Bankova, Bulgarian.
With the desire to study the chemical composition and biological activity of some propolis samples in Vietnam to search for bioactive substances and provide more scientific knowledge about propolis in Vietnam, scientists conducted the project and collected 6 propolis samples, evaluated the cytotoxic and antioxidant activity, the KO-6 sample collected in Binh Dinh (Lisotrigona furva propolis) with good effect, so they were selected for research.
KO-6 Du propolis
Isolate 8 compounds from KO-6 sample, including δ-tocotrienol (1), 3 triterpene: (13E, 17E) -polypoda-7,13,17,21-tetraene-3β-ol (2), hydroxypopanone (7), mangiferolic acid (8); 4 xanthon Cochinchinon A (3), 9-Hydroxycalabaxanthon (4), Cochinchinon I (5), Cochinchinon J (6). Among them, 5 compounds 2, 3, 5-7 were isolated for the first time from Du propolis. The results of chemical research suggest that Craxytolum cochinchinenese and Mangifera indica are the plastic source for Propolis Lisotrigona furva. Results of bioactive test of 5 compounds 2-6 showed that the anti-cancer effect was relatively good on LU lung cancer cell lines, stronger than other cancer cell lines. Among them, there are 2 substances showing selective activity. The most powerful which are 9-Hydroxycalabaxanthon (4) and Cochinchinon I (5) on lung cancer cell line with IC50 values is 4.00 µg/ml.
Compounds isolated from Lisotrigona furva propolis
In addition, scientists have discovered more than 30 compounds, with many being first isolated from propolis. Three species of Dracaena cochinchinensis, C. Namchini (C. cochinchinenese) and the M. indica Mango tree were also discovered as plant sources. Some isolates show good antibacterial and antioxidant activity.
The project has published 3 articles in international journals: 01 article in PLOS ONE magazine (in the SCIE list), 02 articles in international conferences in Croatia and Bulgaria, 01 article in the Journal of Pharmacy; at the same time support training 01 Master and 01 bachelor.
After 2 years of implementation, on August 8, 2019, the topic has been evaluated as Excellent by the Acceptance Council.
The results of this project have important significance in contributing the first scientific data on propolis of Lisotrigona sp. in Vietnam and around the world.
Translated by Tuyet Nhung
Link to Vietnamese version